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parsing bug in hobbit-clients.cfg

list Elmar Heeb
Fri, 19 Nov 2010 17:40:46 +0100
Message-Id: <user-00d3d129a26d@xymon.invalid>

On 11/19/2010 12:53 PM, Elmar Heeb wrote:
Suppose you have the following entry in hobbit-clients.cfg:

HOST=blog.example.com,example.com
PROC apache

then the PROC test will be ignored for example.com. If the two hosts are
reversed, i.e.

HOST=example.com,blog.example.com
PROC apache

then the PROC test will be done for both hosts. I tried with a few
variations on this and it appears that any later string in the comma
separated list will be ignored if it is a substring of a string that
appeared earlier. The same goes for EXHOSTS and probably most other
selectors.

This bug is present in at least versions 4.3.0 beta2 (from Debian
lenny-backports) and 4.2.0 (from Debian lenny).
I have narrowed down the bug to the namematch subroutine in 
lib/matching.c and attached a patch.

The old code (which is the same in 4.2.0 and the svn trunk version) 
indeed explains the wrong behaviour.  Lacking a preceeding comma as a 
guard character essentially made any non-comma character a negating 
match and not just an '!'.  The patch explicitly tests for ",%s," and 
",!%s," and thus makes sure that a partial match cannot prevent a later 
full match.

      -- Elmar


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Dr. Elmar S. Heeb <user-49eb29db847d@xymon.invalid>   support: +41 44 633 26 68
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